1. Field
The described technology relates generally to a mask for thin film deposition and a manufacturing method of an organic light emitting diode (OLED) display.
2. Description of the Related Art
An organic light emitting diode (OLED) display includes a hole injection electrode, an electron injection electrode, and an organic emission layer formed therebetween, and the display emits light as holes injected from an anode and electrons injected from a cathode are recombined to form excitons at the organic light emission layer. The organic light emitting diode (OLED) display device, having high quality properties such as low power consumption, high luminance, a wide viewing angle, a high reaction speed, and the like, is receiving much attention as a next-generation display device for mobile electronic devices.
The organic light emitting diode (OLED) display includes an organic light emitting display panel including a display substrate on which thin film transistors and organic light emitting diodes (OLED) are formed. The organic light emitting diode includes an anode, a cathode, and an organic emission layer. Holes and electrons are injected from the anode and the cathode, respectively, to form excitons, and the excitons make a transition to a ground state, thereby causing the organic light emitting diode to emit light.
In a flat panel display such as the organic light emitting diode (OLED) display, a vacuum deposition method is used for depositing an organic material or metal used as the electrode in a vacuum atmosphere and forming a thin film on a flat plate. In the vacuum deposition method, a substrate on which an organic thin film will be formed is positioned in a vacuum chamber, and an organic material is evaporated or sublimated by using a deposition source unit to deposit it on the substrate.
A deposition mask is used to form an organic layer of a desired shape on the substrate. When an organic material is deposited on a large-sized substrate, a fine metal mask (FMM) may be used as the deposition mask. Since the FMM is a high-definition metal mask having high durability and strength, the organic material can be deposited on the large-sized substrate in a desired pattern.
The FMM may be a deposition mask for depositing an organic material on a large-sized substrate in a high-definition pattern. Using the FMM, a plurality of desired high-definition patterns of organic material can be formed on the substrate all at the same time or concurrently. To deposit the organic material in the desired pattern, the high-definition metal mask may include a plurality of square-shaped slits or a plurality of stripe-shaped slits for allowing the organic material to pass through the FMM. Here, the plurality of square-shaped slits or the plurality of stripe-shaped slits may form a unit masking part, and a plurality of unit masking parts may be provided. A deposition technique using the high-definition metal mask may be used in an organic material deposition and cathode formation process to manufacture the large-sized organic electro-luminescence display device.
To increase the resolution of the organic light emitting diode (OLED) display, the pitch of subpixels of red (R), green (G), and blue (B) are reduced, and to reduce the pitch, an interval between the slots formed in the deposition mask are reduced. However, if the interval within the mask pattern is decreased, a bridge portion of the mask supporting a portion between the slots becomes weak and may be easily broken. Accordingly, it is difficult to manufacture a deposition mask having a high resolution of more than 300 ppi (pixels per inch).
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.